1. Field of the Invention
The present invention relates to a tuned swing type damping device whose mass is swung in tune with shaking of a structure caused by earthquakes, winds, passing vehicles and the like to absorb vibration energy thereof, and more particularly, to a tuned cradle type damping device which has a circular-arc support surface.
2. Description of the Related Art
Regarding structures, there are fixed structures such as buildings, bridges, towers, chimneys, tanks, floodgates and dams, and mobile structures such as ships, aircrafts and vehicles order to deal with shaking of such a structure, which is caused by forces of earthquakes, winds, passing vehicles or the like, there is known a damping device which installs a liquid or mechanical vibration source having weight of 1% or higher of mass of the structure therein, and damps the shaking by tuning shaking of the liquid or mechanical vibration source with the structure, e.g., in Japanese Patent Laid-Open No. Hei 5-256048 or the like.
The above described tuning means coincidence of an intrinsic frequency of the structure with that of the liquid or mechanical vibration source. The vibration source is swung simultaneously with the shaking of the structure to absorb vibration energy thereof. Generally, however, the liquid vibration source needs leakage prevention, and the mechanical vibration source is complex in structure. Consequently, it has not been easy to maintain the conventional damping device always operable by maintenance and inspection.